Carburetor



N. LOMBARD Dec 4, 1928.

CARBURETQR originai Filed July 11, 1924 Patented Dec. 4, 1928.

UNITED? STATES PATENT orrics.

NATI-IANIEL LOMBARD, OF WORCESTER, MASSACHUSETTS, .SSIGNOR T0 LOMBARD CARBURETEB COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

CARBURETOR.

Original application filed July 11, 1924, Serial No. 725,500. Divided and this application :filed November 16, 1925. Serial No. 69,422.

The invention relates to carburetors of the type which lift liquid fuel by suction 'from a source of supply below the level of the fuel nozzle, and this application is a division of my prior application Serial No. 725,500, series of 1915, filed July 11, 1924:,

1 and a continuation, in part, of my copending application Serial No. 656,774, liled August l1, 1923.

The main object of the invention is to provide a carburetor of the above type'that will lift fuel through a. considerable elevation, without creating a detrimentally high vacuum on the intake of theassociated engine, and insuring a proper mixture at'all variations of speed, throttle position, and

Variations in height of the fuel supply. To

attain this object the invention `provides a Venturi passage into which the fuel ports open, thus procuring a powerful suction on the fuel supplyv without any very great vacuum in the mixing chamber. The invention further provides a diaphragm actuated.

valve in the fuel line leading to the aforesaid fuel ports, and this diaphragm con-v trolled valve is adapted, as in the case of similar prior art devices, to exert a controlling` action on the flow of fuel.

I have found, however, that with the elements given above and nothing more, the movement of the diaphragm controlled valve would be magnified by reason of the fact 'that the suction eii'ect of the engine is, so to speak, stepped up in the desire to attain great lifting effect without a high vacuum at the intake, with the result of giving too rich a mixture to the engine at high speeds, if .this valve were not re-controlled by the further mechanism which I have provided. This 'further mechanism consists in a member in the Venturi passage and suction operated means to move said member relative to the walls of the venturi, thus varying the cross sectional area of the restricted portion of the venturi in accordance with the demandbf the engine for the explosive mixture,-this recontrols the acn tion of the diaphragm actuated valve so that the net result is a carburetor of great/lifting power giving al proper mixture under all conditions, and without any excessive back pressure.

Self feeding carburetors are net new, and

I do not claim to be the lirst to use a variable venturi in a carburetor. A successful self feeding carburetor must have a valve controlling the flow of fuel. I believe I am the iirst to see that, in magnifying the lifting' force to attain great lift without excessive back pressure, the ordinary control means for the fuel valve is not enough, but it must be recontrolled as I have outlined, and that this re-control should be self act- ,ing and should respond to the variation of the suction of the engine. Desirably the suction means to move the member in the venturi should 4be created at substantially the same point that the suctionto lift the fuel is taken, in order that a proper synchronization may be attained. In the illustrative embodiment of the invention 'dis closed by the accompanying drawings, and the description relative thereto, this feature is present.

Another object of the invention resides in thespeciiic construction and operation of the movable member inthe venturi, and means to check its movement so that in -turn the recontrol may not be excessive. This, as well as the main object of the invention, is

' claimed herein.

A In the drawings:

Fig. 1 is a vertical sectional view of a carburetor embodying my invention.

Fig. 2 is a horizontal sectional View along 'the line 2-2 of Fig. 1, looking in the direction of the arrows. i y

Fig. 3 is a horizontal sectional View valong theline SW3 of Fig. 1, looking in the direction of the arrows.

Like reference characters refer to like parts in the diil'erent figures. v i

Referring to Fig. l, the casing or shell of the carburetor is generally indicated at l and provides the usual vilange 2 to facilitate its attachment to the intake manifold of the engine, not shown. Air enters the carburetor'at Sand passes through a i/venturi passage l, into a mixing chamber 5 on its way 'to the engine. I show the usual throttle valve at 6. A hollcw cylindricalcasing is secured to the shell 1 below 'the air chamber 3, within which fits a hollow piston 8. The piston 8 is provided with a reduced portion 9 slidable within a sleeve 10 extending up- "i" wardly from vthe casing 7. The reduced lll@ portion 9 of thepiston terminates in a tapering or ogee valve portion 11, around which a collar 12 tightly fits, and these tapering valve parts tend to seat in the throat of the Venturi passage. The parts 11 and 12, by their form, materially heighten the venturi effect when they are slightly withdrawn trom the throat. A coiled spring 13 is received within the portion 9 of the piston 8, and is seated at its lower end on a plate 14 closing the lower end of the casing 7, whereby the pressure ot' the spring 13 tends to vmaintain the piston 8 and the tapering pola tion 11 andcollar 12 in the position shown in Fig. 1.

The valve portion 11 is provided with a central opening 15, within which is slidably received a valve stem 16 extending downwardly from a boss 17 located at the top of the shell 1. The lower end of the stem 16 provides a needle valve portion, 18, which extends into the constrictcd opening' 19 of a tube 2() carried by the valve portion 11. Above the tube 20 is a space 21 in the tapering portion 11, and this space is connected to the Venturi passage by means of a number of y radial and axial passages 22- formed by drilling the tapering portion 11 and grooving its sides before lthe collar 12 is fitted on, see also Fig. 2.

The tube 20 extends downwardlyinto a sleeve 23 rojecting upwardly from the plate 14, andmt lelower end of tube 20 carries a piston 24,` which is slidable within a hollow cylindrical casing 25 which extends below the plate 14 and is preferably integral therewith. .Itywill be apparent that the parts 8, 9, 11,12, 2O and 24,l being attached together move as a unit, in the functioning of the carburetor. o

The end of the casing 25 is closed by a plate 26 which is provided with a central opening 27, normally closed by a check valve 28. The plate 26 is also rovided with passages 29 extending radial yfrom the opening 27, which passages 29 communicate with passages 3() extending upwardly through the walls of the casing 25, whereby the small space 31 above the top of the piston 24 is in communication with the `opening 27.,` The space 31 is also Iincommunication with the interior. of t-he tube 2O through arestricted passage 32 provided in the wall of the tube 20, for a' purpose to be hereinafterdescribed.

The tapering valve portion 11 is also grooved to provide a number of' axial passages 33 betweenit and the-collar 12, as in the case of axial passages 22, but the two sets of passages are not intercommunicating. The )assages 33 connect the Venturiv passage 4 wit the interior of the hollow piston 8 and the chamber inclosed within the casing 7. Figure 2 shows the relative arrangement of passages 22 and The space 34 above the piston 8 is brought into communication with the outside atmospheric pressure, in any suitable manner, such as by an external groove along the portion 9, or a hole through thevhorizontal portion of the sleeve 10 at 34f.

When ,a suction is created by the engine,

the interior of the piston 8 will be subjected` to thisy suction, it being communicated by the passages 33, whereuponthe piston 8 will move ldownwardly against the force of the spring 13. Such downward movement will allow a draft of air, entering at 3, to go through the venturi 4 to the engine, and at the same time, the needle valve proper 18 and the tube 20 having been separated, fuel is suckedthrough the passages 22 and mixes with the air. p

It will be noted that the passages 22 open into the venturi 4 practically at the point of maximum air velocity, and the suction thus created will lift fuel from a tank several feet below this point. In the use of my improved carburetor with automobile engines, it is not sufficient, however, merely to lift the fuel,

but the flow' thereof must be controlled and regulated, and by my invention I have provided means for regulating the flow that is essentially dynamic in its action, so that the results hereinbefore mentioned may be achieved. V

Proceeding with the description'of parts, the plate 26 provides a nipple 35 having an opening 36 in communication with the open-- ing' 27, and the nipple 35 is surrounded by a coupling 37 having a passage 38 extending gagement with a nut 44 secured to the top` of the shell 40, alock nut 45 cooperating with the nipple 43. The nipple 43 has a passage 46, and I desirably provide a cap 47 with an air vent 48 to keep dirt out of the bellows diaphragm 42, while admitting air.

The free end of the bellows 42 is provided with a concave seat 49 which, in the'position oi partsas shown, is justout otcontact with` a ball 50 provided at the upper end of a valve stem 51. The valve stem 51 extends downwardly into an opening 52 provided in the coupling 37, the stem 51 being provided atits lower end with avalve 53. `The valve stem 51 is carried by,a spring 54 j ust below the ball 50' whichVwhcnthe -epgine is not running, Aserves to maintain thel val-ve 53 in yengagement-with a seat 55thereby closing the opening 52. That portion ot the open-Y ing 52 below the valve seat 55 is connected by Leeavea -Howeven the said air and fuel valve mechanism will not respond separately ,to each stroke of the engine on account of the damping action ofthe piston 24, although when an engine with six or more cylinders is equipped with the carburetor of the present invention, this damping piston may be dispensed with. The restricted passage 32 is provided to prevent an accumulation of air difficult to determine anyway, but it isV bubbles in the space 3l above the piston 24 when the latteris functioning. y

The carburetor operates as follows: vWhen the engine to which it is rattached is first turned over, the member in the venturi, consisting of the tapering portion 1l and the collar l2, are held upwardly by the spring 13, and so close the venturi. But fuel can be and is drawn into the engine by Way of the passages 22, and enough air to create a starting mixture can enter by way yof the passages 33. Just when the movable parts 8, 9, 11, 12, 20, and 24: move downwardly varies in different engines according to the power of the starting motor, and is that they have opened a little, anyway, as soon as `the engine starts to run on its own power. When the engine runs slowly, the vacuum in the chambier 7 will not be great, an so the movable parts above will not have opened the venturi greatly. The magnifying factor of the venturi will therefore be great, and the valve 53 will be substantially opened. When the engine speeds up, lthe vacuum in the chamber 7 will be increased, and the venturi will be opened wider,-'thus the magnifying factor will be decreased and the suction exerted to draw the bellows 42 downward and so open the valve 53 wider, while it will inevitably be greater, as it should be, will nevertheless not be so great as it would be if theventuri were `a ,constant area venturi. This re-control of thefuel flow results in a good mixture safe to say lat all speeds, since without tlus re-control,

the mixture would be `excessive at high speeds, or else leanatl low speeds.

"lhe exact quantitative nature of this recontrol is difficult to determine, but 'the carhuretor shown in the accompanying drawings has been found to give excellent practical results. Therefore l connue myself to indi- The functioning of thedeviceis rendered very smooth by reason of the dash pot de-l vice embodied inv the cylinder 25 and piston 2l. This prevents violent movements of the parts 8, 9, 1l, l2, 20, and 24 and thus the rec-ontrol is in effect dampened, and an engine to which the carburetor is attached will run smoothly despite the pulsatingnature of the suction created by the engine.

` I claim,

1l. ln a carburetor of the type that lifts liquid fuel from a source below the level of the fuel nozzle, a `Venturi passage, a Ifuel entrance' port opening into said Venturi passage at approximately the point of greatest speed of flow of air, thus creating a suction on the fuel which is greater than the vacuum created by the associated engine on thcvcarburetor side of the throttle valve, a

'responsive device beingactuated and controlled by the suction created in the aforesaid fuel entrance port opening into the said venturi, whereby the valve controlled by the device moves to admit more or less fuel responsive to the changing engine suction and the magnification thereof caused by the lcnt-rance port opening into the said venturi,

a member in said venturi, and air pressure means for moving said member kin relation to the walls of said venturi, said air pressure means being operated by thefsuction created ,by the associated engine, whereby to vary the cross sectional area of said venturi where said fuel port opens thereinto, thus preventing excessive action andpreaction of 'the pressure responsive device .controlled valve 'responsive to changes in the ydemand for fuel by reason of variation 'of speed ofthe assoc-iies ated engine and changes in the position of buretor side of the throttle valve, a fuel line,

including suitable connections, connecting said port to the fuel supply, L valve vin saidy fuel line, -a pressure responsive device to operate said valve, the said pressure responsive device being actuated and controlledby the suction created in the aforesaid fuel en 'trance port opening into the said venturi," whereby the valve controlled by the device moves to admit more or less fuel responsive to the changing vengine suction and the magnilication thereof causedby the entrance ort lopening into the said venturi, a memer in said venturi, an air passage opening l into said venturi adjacent the said fuel port, air pressure operated means operated by the reduction of pressure at the said air passage, said air pressure means being connected to said member to move itin' relation to the walls of said venturi, whereby to vary the cross sectional area of saidv venturi where said fuel port opens thereinto the said area being thus regulated in accordance with the reduction of pressure at that point, thus preventing excessive action and reaction of the pressure responsive device controlled valve responsive to changes inthe demand for fuel by 'reason of variation of speed of the associated engine and changes in the position of the main throttle valve.

3. In a carburetor, a valve to control the supply of air and liquid fuel, a pair of pistons directly connected to said valve and movable therewith as a unit, cy1indersI in which said pistons operate, separate passages through said valve leading to said cylinders, one passage admitting the depression in the carburetor to one cylinder to draw said unit against the flow of air, the otherpassage in said valve carrying liquidfuel from the other cylinder, where the fuel produces al dash pot effect on the other piston, and a needle valve projecting into said second passage, so as to control simultaneously both the air and fuel by movement of the single valve member.

4. In a carburetor, a conical or ogee valve to control the supply of air and liquid fuel, an orifice adapted to receive. said valve, a spring to force said valve against said orifice when the carburetor is inactive,a pair of pistons directly connected to said valve and movable therewith as a unit, cylinders in which said pistons operate, separate passages through said valve leading to said cylinders, one passage admitting'the depression inthe carburetor to one cylinder to draw said unit against the flow of the air, the other passage in said valve carrying liquid feul from the other cylinder, where the fuel -produces a dash pot effect on the other piston, and a.

needle valve projecting into said second pas- .sage so as to control simultaneously both the air and fuel by movement of the single valve member.

Dated this twelfth day of November, 1925.

, NATHANIEL LOMBARD. 

